I've noticed that I feel a little ashamed when I shoot down a car behind me or swat somebody, because shooting backwards and using the swatter seem cowardly to me. It's probably because if somebody is behind me, they're at a disadvantage compared to me and it's mean to bully the disadvantaged. So, I developed this concept of STK Chivalry, which means never shooting backwards and only using the swatter to get rid of a bomb, a parachute, etc. but not to swat others.
It could be used as an achievement (you won 10 consecutive races while following the rules of chivalry!) or as an online handicap which would simply not allow you to do these things. Alternatively, all players could decide to play this way.
To clarify, I don''t think shooting backward or swatting people is bad or not fun. I just think that optionally not doing it is another way to enrich STK.